Error correction for display device

Abstract

A display device has an image processing unit that determines an error for a pixel location that is based on the difference between an input color dataset and an output color dataset. The error is fed back to the image processing unit to propagate and spread across other neighboring pixel locations. In generating the output color dataset, an error-modified dataset that includes the input dataset and the error may first be generated. The error-modified dataset is examined to ensure the color values fall within the display gamut. The color dataset is also quantized and dithered to make the output dataset having a bit depth that is compatible with what the light emitters can support. Lookup tables and transformation matrices may also be used to account for any potential color shifts of the light emitters due to different driving conditions such as driving currents.

What is claimed is: 
     
       1. A method for operating a display device, comprising:
 receiving a first input color dataset representing a color value intended to be displayed at a first pixel location; 
 generating, from the first input color dataset, a first output color dataset for driving a first set of light emitters that emit light for the first pixel location; 
 determining a first error correction dataset representing a first compensation of color error of the first set of light emitters resulting from a difference between the first input color dataset and the first output color dataset; 
 receiving a second input color dataset for a second set of light emitters that emit light for a second pixel location, the second set of light emitters comprising a first subset of light emitters that emit light in a first color range defined by a first gamut, and the second set of light emitters further comprising a second subset of light emitters that emit light in a second color range defined by a second gamut, the first gamut different from the second gamut; 
 converting, using values in the first error correction dataset, the second input color dataset to an error-modified second color dataset; 
 splitting the error-modified second color dataset into a first sub-dataset and a second sub-dataset, the first sub-dataset corresponding to most significant bits (MSBs) in the error-modified second color dataset and the second sub-dataset corresponding to least significant bits (LSBs) in the error-modified second color dataset, wherein the first subset of light emitters is configured to emit light corresponding to values in the first sub-dataset and the second subset of light emitters is configured to emit light corresponding to values in the second sub-dataset; 
 determining a first output color coordinate for the first subset of light emitters; 
 determining a second output color coordinate for the second subset of light emitters; 
 responsive to determining that the first or the second output color coordinate falls outside of a common color gamut that represents ranges of colors of the display device, performing mapping of the error-modified second color dataset to an adjusted error-modified second color dataset that is within the common color gamut, the common color gamut being an overlapping area of the first gamut and the second gamut; 
 generating, from the adjusted error-modified second color dataset, a second output color dataset for driving the second set of light emitters that emit light for the second pixel location; and 
 generating a second error correction dataset for a third set of light emitters to compensate the difference between the second input color dataset and the second output color dataset, the second error correction dataset resulted at least from the mapping of the error-modified second color dataset to the adjusted error-modified second color dataset. 
 
     
     
       2. The method of  claim 1 , wherein the difference between the first input color dataset and the first output color dataset is caused at least by a quantization of driving currents of the first set of light emitters that exhibit shifts of color. 
     
     
       3. The method of  claim 2 , wherein generating the first output color dataset comprises using one or more look-up tables, the look-up tables compensate the shifts of color to determine the first output color dataset. 
     
     
       4. The method of  claim 1 , wherein the first subset of light emitters are driven at a first current level and the second subset of light emitters driven at a second current level different from the first current level, driving the first subset at the first current level causing the first subset of light emitters to emit light defined by the first gamut and driving the second subset at the second current level causing the second subset of light emitters to emit light defined by the second gamut. 
     
     
       5. The method of  claim 4 , wherein the first subset of light emitters are driven by first pulse width modulation (PWM) signals at the first current level and the second subset of light emitters are driven by second PWM signals at the second current level. 
     
     
       6. The method of  claim 1 , wherein generating the first output color dataset comprises:
 splitting a version of the first input color dataset into a first input color subset and a second input color subset; 
 adjusting the first input color subset using a first correction matrix that accounts for a first color shift; and 
 adjusting the second input color subset using a second correction matrix that accounts for a second color shift. 
 
     
     
       7. The method of  claim 6 , wherein the first output color dataset is a combination of the first input color subset and the second input color subset, the first input color subset corresponds to most significant bits of the first output color dataset, and the second input color subset corresponds to least significant bits of the first output color dataset. 
     
     
       8. The method of  claim 6 , wherein adjusting the first input color subset using the first correction matrix maps a first color coordinate represented by values of the first input color subset from the common color gamut to the first gamut, and adjusting the second input color subset using the second correction matrix maps a second color coordinate represented by values of the second input color subset from the common color gamut to the second gamut. 
     
     
       9. The method of  claim 1 , wherein determining the first error correction dataset comprises:
 determining an error being the difference between the first output color dataset and a version of the first input color dataset; and 
 passing the error through an image kernel to generate the first error correction dataset. 
 
     
     
       10. The method of  claim 9 , wherein the image kernel is a Floyd-Steinberg dithering kernel. 
     
     
       11. The method of  claim 10 , wherein the version of the first input color dataset is an error-modified color dataset that is generated from the first input color dataset adding error values determined from other previous pixel locations. 
     
     
       12. The method of  claim 1 , wherein the mapping of the error-modified second color dataset to the adjusted error-modified second color dataset that is within the common color gamut is a constant-hue mapping. 
     
     
       13. The method of  claim 1 , wherein generating the first output color dataset further comprises:
 splitting a version of the first input color dataset into a first input color subset and a second input color subset; 
 scaling the first input color subset with a first scale factor, the first scale factor representing a first compensation for a first non-uniformity of a first subset of the first set of light emitters; and 
 scaling the second input color subset with a second scale factor that is different from the first scale factor, the second scale factor representing a second compensation for a second non-uniformity of a second subset of the first set of light emitters. 
 
     
     
       14. The method of  claim 1 , wherein the first error correction dataset comprises data values for adjusting a plurality of pixel locations neighboring the first pixel location, and the second pixel location is one of the plurality of pixel locations neighboring the first pixel location. 
     
     
       15. The method of  claim 1 , wherein the light emitters of the first set and the second set are light emitting diodes (LEDs) that exhibit color shifts when different levels of current drive the light emitters. 
     
     
       16. A display device, comprising:
 a first set of light emitters configured to emit light for a first pixel location; 
 a second set of light emitters configured to emit light for a second pixel location, the second set of light emitters comprising a first subset of light emitters that emit light in a first color range defined by a first gamut, and the second set of light emitters further comprising a second subset of light emitters that emit light in a second color range defined by a second gamut, the first gamut different from the second gamut; and 
 an image processing unit configured to:
 receive a first input color dataset representing a color value intended to be displayed at the first pixel location; 
 generate, from the first input color dataset, a first output color dataset for driving the first set of light emitters; 
 determine a first error correction dataset representing a first compensation of color error of the first set of light emitters resulting from a difference between the first input color dataset and the first output color dataset; 
 receive a second input color dataset for the second set of light emitters that emit light for the second pixel location; 
 convert, using values in the first error correction dataset, the second input color dataset to an error-modified second color dataset; 
 split the error-modified second color dataset into a first sub-dataset and a second sub-dataset, the first sub-dataset corresponding to most significant bits (MSBs) in the error-modified second color dataset and the second sub-dataset corresponding to least significant bits (LSBs) in the error-modified second color dataset, wherein the first subset of light emitters is configured to emit light corresponding to values in the first sub-dataset and the second subset of light emitters is configured to emit light corresponding to values in the second sub-dataset; 
 determine a first output color coordinate for the first subset of light emitters; 
 determine a second output color coordinate for the second subset of light emitters; 
 responsive to determining that the first or the second output color coordinate falls outside of a common color gamut that represents ranges of colors of the display device, perform mapping of the error-modified second color dataset to an adjusted error-modified second color dataset that is within the common color gamut, the common color gamut being an overlapping area of the first gamut and the second gamut; 
 generate, from the adjusted error-modified second color dataset, a second output color dataset for driving the second set of light emitters; and 
 generate a second error correction dataset for a third set of light emitters to compensate the difference between the second input color dataset and the second output color dataset, the second error correction dataset resulted at least from the mapping of the error-modified second color dataset to the adjusted error-modified second color dataset. 
 
 
     
     
       17. The display device of  claim 16 , wherein the first set of light emitters and the second set of light emitters are part of a display panel that uses an analog modulation to drive light emitters of the display panel, the analog modulation adjusts current levels to control light intensity of the light emitters of the display panel. 
     
     
       18. The display device of  claim 17 , wherein the light emitters of the display panel exhibits shifts of color when driven by different current levels and generate the first output color dataset comprises using one or more look-up tables, the look-up tables compensate the shifts of color to determine the first output color dataset. 
     
     
       19. The display device of  claim 16 , wherein the first set of light emitters is part of a display panel that uses a hybrid modulation to drive first set of light emitters, the hybrid modulation drives a first subset of light emitters of the first set using a first current level and drives a second subset of light emitters of the first set using a second current level. 
     
     
       20. The display device of  claim 19 , wherein the first subset of light emitters are driven by first pulse width modulation (PWM) signals at the first current level and the second subset of light emitters are driven by second PWM signals at the second current level. 
     
     
       21. The display device of  claim 19 , wherein generate the first output color dataset comprises:
 split a version of the first input color dataset into a first input color subset for the first subset of light emitters and a second input color subset for the second subset of light emitters; 
 adjust the first input color subset using a first correction matrix that accounts for a first color shift of the first subset of light emitters driven by the first current level; and 
 adjust the second input color subset using a second correction matrix that accounts for a second color shift of the second subset of light emitters driven by the second current level. 
 
     
     
       22. An image processing unit of a display device, comprising:
 an input terminal configured to receive input color datasets for different pixel locations, each input color dataset representing a color value intended to be displayed at a corresponding pixel location; 
 an output terminal configured to transmit output color datasets to a display panel of the display device, each output color dataset configured to drive a set of light emitters; and 
 a data processing unit configured to:
 determine, a difference between a first input color dataset and a first output color dataset corresponding to a first pixel location; 
 determine a first error correction dataset based on the difference; 
 receive a second input color dataset for a second set of light emitters that emit light for a second pixel location, the second set of light emitters comprising a first subset of light emitters that emit light in a first color range defined by a first gamut, and the second set of light emitters further comprising a second subset of light emitters that emit light in a second color range defined by a second gamut, the first gamut different from the second gamut; 
 convert, using values in the first error correction dataset, the second input color dataset to an error-modified second color dataset; 
 split the error-modified second color dataset into a first sub-dataset and a second sub-dataset, the first sub-dataset corresponding to most significant bits (MSBs) in the error-modified second color dataset and the second sub-dataset corresponding to least significant bits (LSBs) in the error-modified second color dataset, wherein the first subset of light emitters is configured to emit light corresponding to values in the first sub-dataset and the second subset of light emitters is configured to emit light corresponding to values in the second sub-dataset; 
 determine a first output color coordinate for the first subset of light emitters; 
 determine a second output color coordinate for the second subset of light emitters; 
 responsive to determining that the first or the second output color coordinate falls outside of a common color gamut that represents ranges of colors of the display device, perform mapping the error-modified second color dataset to an adjusted error-modified second color dataset that is within the common color gamut, the common color gamut being an overlapping area of the first gamut and the second gamut; 
 generate, from the adjusted error-modified second color dataset, a second output color dataset for driving the second set of light emitters; and 
 generating a second error correction dataset for a third set of light emitters to compensate the difference between the second input color dataset and the second output color dataset, the second error correction dataset resulted at least from the mapping of the error-modified second color dataset to the adjusted error-modified second color dataset.